CODEWITHSUNDEEP
c++stringspace
Christian
Christian

Reputation: 593

Testing for a space character inside a string...?

I'm trying to test if a character in a string is a space, and I'm getting extremely frustrated:

string my_string;
cin >> my_string;
for (int i = 0; i < my_string.length(); i++)
    {
        if (my_string[i] == ' ') // this never becomes true...
        {
            cout << "this text should pop, but never does" << endl;
        }
    }

I'm not getting any errors and I've looked online, but people on different forums say this is how to test for a space. Uh.

Upvotes: 1

Views: 359

Answers (3)

Pepe
Pepe

Reputation: 6480

Thats because cin stops reading at the first whitespace so you never actually read the entire sentence but the first word. Use getline instead.

std::string my_string;
std::getline(std::cin, my_string);
for (int i = 0; i < my_string.length(); i++)
    {
        if (my_string[i] == ' ') // this never becomes true...
        {
            std::cout << "this text should pop, but never does" << std::endl;
        }
    }

Upvotes: 5

Benoit
Benoit

Reputation: 79185

Additionnally to test whether a space is present use std::string::find!

std::string my_string;
std::cin >> my_string; // please do not use « using namespace std; » if possible
size_t space_position = my_string.find(' ');
if(space_position != std::string::npos)
{
    std::cout << "found space" << std::endl;
}

Upvotes: 2

wilhelmtell
wilhelmtell

Reputation: 58677

when you say

cin >> my_string;

you are taking formatted input. std::cin discards any whitespace in that line, and it reads up to and yields only a single word.

try instead

std::string my_string;
std::getline(std::cin, my_string);

to get a single line, or

#include <iterator>

// ...
std::string my_string((std::istreambuf_iterator<char>(std::cin)),
                      std::istreambuf_iterator<char>());

to get everything up to an end-of-file mark into the string.

Upvotes: 8

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